Electromagnetic explosionproof vibratory head



Nov. 10, 1964 w. s. KOKE 3,156,336

mcwaomnmc EXPLOSIONPROOF VIBRATORY HEAD Filed Nov. 25, 1959 2 Sheets-Sheet 2 INVEN TOR.

{fa/2 er- 5. fi oie al-fer 3 QI-Zer United States Patent 3,156,836 ELECTROMAGNETIC EXPLOSIGNPRGOF VIBRATORY HEAD Walter S. Koke, Homewood, IiL, assignor to Novo Industrial Corporation, a corporation of New York Filed Nov. 25, 1959, Ser. No. 855,449 1 Claim. (Cl. 31029) This invention relates to an explosionproof electromagnetic vibrating head.

One purpose of the present invention is an explosionproof vibrating head wherein all electrical connections are sealed within the housing with rnetal-to-rnetal contacts on all sealing surfaces.

Another purpose is a compact and efiicient electromag netic vibrating head.

Another purpose is a wear-resistant, simply constructed improved vibrating head for use in screening applications and the like.

Another purpose is an explosionproof vibrating head wherein the electromagnet and electrical connections therefor are completely sealed with metal-to-metal contacts on all sealing surfaces.

Another purpose is an electromagnetic vibrating head wherein the electromagnet is completely sealed off from the vibrating armature with metal-to-metal contact seals.

Other purposes will appear in the ensuing specification, drawings and claim.

The invention is illustrated diagrammatically in the following drawings wherein:

FIGURE 1 is a side view, in half section, of an electromagnetic vibrating head, and

FIGURE 2 is a section along line 2-2 of FIGURE 1.

A housing is suitably connected, through bolts or the like not shown, to an intermediate wall or plate 12 and a base or cover plate 14 to form the outer structure for a vibrating head.

Within the housing 10 is an electromagnet indicated generally at 16 including a generally U-shaped core 13 comprising, as shown in the drawings, vertical core extensions 20 and a horizontal connecting portion 22. in the preferred form, the core portion 22 may be suitably embedded within top wall 24 of the housing 10. The sides 26 of the housing extend downwardly a suificient dis tance so that the bottom surface thereof lie in the same plane as the bottom surface of the core extensions 20. When forming the housing and core shown herein, the housing may be cast around the core after which both the core extensions and the housing sides are machined so that they are flush or lie in the same plane. Thus the intermediate plate 12 will fit firmly against both the sides of the housing and the core extensions 20.

Each of the core extensions are surrounded by an electrical coil 28 so that the core and coils form an electromagnet. A coil retainer 30 is positioned between each core extension and the turns of wire forming the coil to provide a spool or the like upon which the coil is wound. In the preferred form a thin layer of plastic 32, which may be an epoxy or otherwise, is positioned between the turns of Wire and the coil retainer 30. Suitable leads or wires 34 pass through a fitting 36 in the housing It). The fitting and leads are preferably arranged in an explosionproof connection.

The intermediate plate or wall 12 which completely closes one end of the housing 10 to form a closed chamber 38, is preferably formed of a non-magnetic substance having low permeability, and high electrical resistance, for example, a nickel steel. Being non-magnetic, the wall 12 will not short circuit the magnetic circuit formed by the electromagnet. The center of the plate 12 has an chamber.

"ice

upwardly bent portion 4% which is adapted to receive the head of the stem hereinafter described.

An armature 4-2 is suitably positioned beneath the intermediate plate 12 and generally adjacent the center of the vibrating head. The armature is suspended by means of leaf springs 44 or the like for vibratory movement toward and away from the intermediate wall 12. As shown in FIGURE 1, screws 46 or the like secure the leaf springs 44 to the armature 42. The leaf springs 44 are suitably supported at opposite ends thereof by spring holders 48. In the preferred form the spring holders 48 are formed with an upper portion 50 and a lower portion 52 secured together by means of mounting bolts 54. The bolts 54 mount the spring holders on wall extensions 56 projecting inwardly from the sides of the cover or base plate 14.

A suitable stem 58, which may be mounted at one end thereof to a screening device or the like or other machine requiring vibratory motion, has an integral threaded portion 6% at the opposite end to secure the stem to the armature 42. The top of the portion 64 has been upset to provide a secure connection. The stem extends through an opening 62 in the bottom wall 66 of the base plate 14.

A gasket or boot 68 encloses a portion of the stem 58 and has an upwardly extending annular portion 70 which fits tightly within the opening 62 and an annular flangelike portion 72 which surrounds the opening 62. The intermediate area 74 of the gasket is folded to provide for movement of the stem and the lower portion 76 is somewhat solid to enclose an annular stem projection 78. The gasket is held at the upper end thereof by the annular portion 70, tightly received within the opening 62, and at the lower end by the somewhat solid portion 76 which encloses the annular projection 78.

The use, operation and function of the invention are as follows:

Shown and described herein is an improved explosionproof electromagnetic vibrating head. All of the electrical connections for the electromagnet are in the complete ly closed and sealed chamber 38 with metal-to-metal surface on all contact surfaces. The armature and the electromagnet providing the attracting force therefor are separated by a non-magnetic intermediate wall having low permeability. The intermediate wall 12 thus seals the open end of the housing 10, and as it is formed of a nonmagnetic material, does not short circuit the core extensions seated thereon. The wall 12 does not therefore reduce the force of the electromaget applied to the armature. The particular material of which the wall 12 may be formed will vary, however, stainless steel or nickel steel have been found to be satisfactory. These materials have the requisite non-magnetic properties while providing a tough surface to withstand wear and impact.

In forming the vibrating head as shown herein the housing is cast around the core after which the core extensions and housing are machined, usually by grinding, so that they lie in the same plane thus providing flush surfaces against which the intermediate wall 12 may be positioned. The wall 12 firmly abuts both the core extensions and the sides of the housing.

A second chamber if formed by the cover plate or base 14 and the intermediate wall 12. This chamber contains the armature and the supporting spring structure. The magnetic fields formed by the coil and core will alternately attract and release the armature so that the armature will vibrate at a relatively high frequency in the lower The frequency of vibration of the armature will depend upon the frequency of the electric signal applied to the coils and the natural period of vibration of the spring assemblies. The vibrating head may be operated so that the armatures strike the lower surface of the intermediate wall 12 or it may be operated so that it stops short of this surface. The vibrating head is designed for either application as intermediate wall 12 is formed of a highly wear-resistant and tough material. Additionally, the core extensions provide support for the plate 12 when the head is operated so that the armature strikes the plate.

The stem which is secured to the armature and extends down to the cover plate will vibrate with the armature. The end of the stern not shown, may be connected to a screening assembly or similar device requiring vibratory motion. The device shown herein will provide vibration having harmonic motion in that the natural period of vibration of the spring assemblies will combine with the frequency of the electric signal applied to provide harmonic vibratory motion. As shown in the drawings, the invention discloses the use of two coils surrounding two core extensions. However the partciular construction of the electromagnet is not essential to the invention and there may be only one coil or there may be more. In addition, the armature structure has two springs forming the support therefor. Again, there may be more or less as the number of springs is not essential to the invention.

One importantfeature is the metal-to-metal contact at the seals. This is to say that no organic seals such as rubber or resilient'O rings are used which will deteriorate. In my arrangement I draw the sealing surfaces tightly together by screws or bolts, and sufficient contact area is provided sothat a tight permanent seal is provided which will not deteriorate or otherwise be affected by Weather or age. The bolts or screws, not shown, may be countersunk and may extend through the flange portions of the housing 10, and cover plate 14 and through the outer edge of the intermediate plate 12.

Whereas the preferred form of the invention has been shown and described herein, it should be realized that there are many modifications, substitutions and alterations thereto within the scope of the following claim.

I claim:

An explosionproof vibrating head including a housing divided into two chambers by a thin and substantially flat intermediate non-magnetic wall, said intermediate wall being of low permeability and completely sealing said two chambers, one from the other, a core positioned in one of said chambers, said core having a portion, remote from said intermediate wall, which is embedded within said housing and secured thereto, said core further having portions which extend toward and bear against said intermediate wall, a coil positioned on said core to form an electromagnet therewith, electrical connections for said coil passing through said housing, an armature, a plurality of eaf spring assemblies suspending the armature in said other chamber of the housing in predetermined spaced relation to said intermediate wall when at rest, said armature having a generally central projection extending toward said intermediate wall, said intermediate wall having a generally central cavity for receiving said projection when said armature is moved toward said intermediate wall.

References Cited in the file of this patent UNITED STATES PATENTS 2,556,854 Spears et al June 12, 1951 2,790,097 Hopkins e Apr. 23, 1957 2,913,988 White Nov. 24, 1959 3,014,165 Kolte Dec. 19, 1961 

